TL;DR
If you only read this section:
• A window qualifies for ENERGY STAR in Canada if:
– U-Factor ≤ 1.22 W/m²·K
OR
– ER ≥ 34
• Example NTI performance:
– U-Factor: 1.02
– ER: 40
– SHGC: 0.39
– VT: 0.46
– Air Leakage: ≤ 0.10
ENERGY STAR is the minimum requirement.
Understanding performance is how you compare properly.
What Makes a Window ENERGY STAR Certified in Canada?
In Canada, ENERGY STAR certification is regulated by Natural Resources Canada.
A window qualifies if it meets one of these thresholds:
• U-Factor ≤ 1.22 W/m²·K
OR
• Energy Rating (ER) ≥ 34
There is no minimum requirement for SHGC.
There is no minimum requirement for Visible Transmittance.
Those numbers influence performance, but they are not required for certification.
This is important because not all ENERGY STAR windows perform the same. Meeting the minimum simply means the window qualifies.
The 5 Ratings You Should See on Every Quote
When comparing window replacement quotes in Ontario, these five numbers matter most.
If they are not listed, ask for them.
1. U-Factor (Thermal Transmittance)
Measures how much heat passes through the window assembly.
Lower number = better insulation.
ENERGY STAR path:
≤ 1.22 W/m²·K
NTI example:
1.02 W/m²·K
What this means:
• Warmer interior glass in winter
• Reduced heat loss
• Greater comfort near windows
2. Energy Rating (ER)
The ER rating is a Canadian-developed performance score.
It combines:
• U-Factor
• Solar heat gain
• Air leakage
Minimum requirement:
ER 34
NTI example:
ER 40
An ER of 40 represents strong, well-balanced performance for Ontario’s climate (Zone 5).
3. Solar Heat Gain Coefficient (SHGC)
Measures how much solar heat enters your home.
No minimum requirement for ENERGY STAR.
NTI example:
0.39
In Ontario, balanced SHGC (often around 0.35–0.45 depending on orientation) helps:
• Capture useful winter warmth
• Reduce summer overheating
Window direction matters. South-facing glass performs differently than west-facing glass.
4. Visible Transmittance (VT)
Measures how much visible daylight passes through the glass.
No minimum requirement under ENERGY STAR.
NTI example:
0.46
This level maintains clarity while supporting overall thermal performance.
5. Air Leakage (AL)
Measures how much air passes through the window assembly.
Lower = fewer drafts.
NTI example:
≤ 0.10
Draft complaints are often caused by air leakage — not insulation alone.
Installation quality directly affects this metric.
Fixed Windows vs Operating Windows
Fixed (non-operating) windows typically achieve higher energy and sound ratings because they have no moving parts.
When comparing quotes, ensure you are comparing similar window types.
A fixed unit will usually outperform a sliding unit on paper.
Where NTI Window Packages Rank
Our window packages are designed specifically for Ontario’s climate.
Example performance:
| Metric | ENERGY STAR Minimum | NTI Example |
|---|---|---|
| U-Factor | ≤ 1.22 | 1.02 |
| ER | ≥ 34 | 40 |
| SHGC | No minimum | 0.39 |
| VT | No minimum | 0.46 |
| Air Leakage | Tested metric | ≤ 0.10 |
Higher-performance configurations are available depending on project goals.
All packages meet ENERGY STAR requirements. Some configurations exceed them.
Energy Efficiency vs Comfort
Energy efficiency is about heat transfer.
Comfort includes:
• Interior glass temperature
• Draft control
• Solar balance
• Proper measurement
• Correct installation
A well-installed window system will outperform a higher-rated product installed poorly.
Experience matters.
What About Noise?
ENERGY STAR focuses on thermal performance.
Noise reduction is measured using STC (Sound Transmission Class).
Typical building code minimum:
STC 32
NTI configurations (select packages):
Up to STC 38
Higher STC ratings reduce exterior noise such as traffic and lawn equipment.
If sound control is important, it should be part of the quoting discussion.
Questions to Ask When Comparing Window Quotes
• What is the U-Factor for this specific configuration?
• What is the ER rating?
• What is the Air Leakage rating?
• Are these ratings tested for Ontario (Zone 5)?
• Are these numbers for this exact operating style?
Clear answers indicate a transparent process.
The Bottom Line
A window qualifies for ENERGY STAR at ER 34.
That is the minimum.
Performance above that depends on:
• Glass configuration
• Window style
• Orientation
• Installation quality
At NTI Windows & Doors, we focus on clear performance data, proper measurement, and installation accountability.